U.S. patent application number 14/664185 was filed with the patent office on 2015-10-01 for shovel.
The applicant listed for this patent is Sumitomo Heavy Industries, Ltd.. Invention is credited to Kentaro Furusho, Kazunori Hiranuma, Takeshi Okada, Yoshitaka Shizu.
Application Number | 20150276044 14/664185 |
Document ID | / |
Family ID | 54163600 |
Filed Date | 2015-10-01 |
United States Patent
Application |
20150276044 |
Kind Code |
A1 |
Furusho; Kentaro ; et
al. |
October 1, 2015 |
SHOVEL
Abstract
A shovel includes: a speed reducer configured by stacking a
plurality of gear speed reducers each having a sun gear, a
planetary gear, an internal gear, and a carrier member supporting
the planetary gear provided in a case, in a direction of an axis of
rotation of an upper turning body; and a movement restriction
section which is provided between the sun gear of one gear speed
reducer among the gear speed reducers stacked in a plurality and
another gear speed reducer stacked so as to face the sun gear and
restricts movement of the sun gear of the one gear speed reducer
toward the other gear speed reducer, wherein the movement
restriction section is provided at the case.
Inventors: |
Furusho; Kentaro; (Kanagawa,
JP) ; Hiranuma; Kazunori; (Kanagawa, JP) ;
Okada; Takeshi; (Kanagawa, JP) ; Shizu;
Yoshitaka; (Aichi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sumitomo Heavy Industries, Ltd. |
Tokyo |
|
JP |
|
|
Family ID: |
54163600 |
Appl. No.: |
14/664185 |
Filed: |
March 20, 2015 |
Current U.S.
Class: |
475/331 |
Current CPC
Class: |
E02F 9/123 20130101;
F16H 2057/085 20130101; F16H 1/46 20130101; E02F 9/2095 20130101;
E02F 9/128 20130101; F16H 57/08 20130101 |
International
Class: |
F16H 57/08 20060101
F16H057/08; E02F 9/12 20060101 E02F009/12; F16H 1/46 20060101
F16H001/46 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2014 |
JP |
2014-064651 |
Claims
1. A shovel comprising: a speed reducer configured by stacking a
plurality of gear speed reducers each having a sun gear, a
planetary gear, an internal gear, and a carrier member supporting
the planetary gear provided in a case, in a direction of an axis of
rotation of an upper turning body; and a movement restriction
section which is provided between the sun gear of one gear speed
reducer among the gear speed reducers stacked in a plurality and
another gear speed reducer stacked so as to face the sun gear and
restricts movement of the sun gear of the one gear speed reducer
toward the other gear speed reducer, wherein the movement
restriction section is provided at the case.
2. The shovel according to claim 1, wherein the movement
restriction section is a plate-shaped member fixed to the case.
3. The shovel according to claim 1, wherein a slide bearing member
is provided between the movement restriction section and the sun
gear.
4. The shovel according to claim 3, wherein the slide bearing
member is a thrust washer or a thrust bearing.
Description
RELATED APPLICATIONS
[0001] Priority is claimed to Japanese Patent Application No.
2014-064651, filed Mar. 26, 2014, the entire content of which is
incorporated herein by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] A certain embodiment of the invention relates to a shovel
having a turning speed reducer.
[0004] 2. Description of Related Art
[0005] A shovel is provided with a turning drive device which
drives an upper turning body so as to turn it. The turning drive
device often reduces the power from a power source (a hydraulic
motor, an electric motor, or the like) in a turning speed reducer
(hereinafter referred to simply as a speed reducer) and turns the
upper turning body by increased output torque.
[0006] As the speed reducer, in terms of being compact, in terms of
a change in reduction ratio being easy, or the like, a planetary
gear speed reducer in which a sun gear is used as an input element
and a planetary carrier of a planetary gear is used as an output
element is frequently used. Further, in order to obtain a
predetermined reduction ratio, a multistage speed reducer in which
a plurality of planetary gear speed reducers are stacked is also
frequently used (refer to the related art).
SUMMARY
[0007] According to an aspect of the present invention, there is
provided a shovel including: a speed reducer configured by stacking
a plurality of gear speed reducers each having a sun gear, a
planetary gear, an internal gear, and a carrier member supporting
the planetary gear provided in a case, in a direction of an axis of
rotation of an upper turning body; and a movement restriction
section which is provided between the sun gear of one gear speed
reducer among the gear speed reducers stacked in a plurality and
another gear speed reducer stacked so as to face the sun gear and
restricts movement of the sun gear of the one gear speed reducer
toward the other gear speed reducer, wherein the movement
restriction section is provided at the case.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a side view of a shovel according to an embodiment
of the present invention.
[0009] FIG. 2 is a block diagram showing the configuration of a
drive system in an embodiment of the present invention.
[0010] FIG. 3 is a block diagram showing the configuration of a
turning drive device in an embodiment of the present invention.
[0011] FIG. 4 is a top view of the turning drive device.
[0012] FIG. 5 is a cross-sectional view along a line V-V in FIG.
4.
[0013] FIG. 6 is a cross-sectional view showing the vicinity of a
movement restriction mechanism in the turning drive device in an
enlarged manner.
DETAILED DESCRIPTION
[0014] A planetary carrier is supported on a case by a bearing
member (a bearing or the like), whereby the movement of the
planetary carrier in a thrust direction (an axial direction) is
restricted. However, a shovel is used in a harsh environment, and
thus there is a concern that a great external force may be applied
to a lower traveling body and an upper turning body during
work.
[0015] In a case where the external force is applied, a low-speed
side sun gear provided in a low-speed planetary gear speed reducer
disposed on the lower side is sometimes biased so as to move toward
a high-speed planetary gear speed reducer disposed at an upper
portion. The movement and biasing force is applied to the bearing
member through a high-speed side planetary carrier. Accordingly,
there is a problem in that there is a concern that the bearing
member may be damaged due to the movement and biasing force.
[0016] It is desirable to provide a shovel in which a bearing
member supporting a carrier member is prevented from being
damaged.
[0017] According to a certain aspect of the present invention, the
movement of a carrier member in a thrust direction is restricted,
and thus a bearing member can be prevented from being damaged.
[0018] Next, a non-limiting exemplary embodiment of the present
invention will be described with reference to the accompanying
drawings.
[0019] In addition, in the description in all the accompanying
drawings, the same or corresponding members or components are
denoted by the same or corresponding reference numerals and
overlapping description is omitted. Further, the drawings are not
intended to show the relative ratio between members or components
unless otherwise specified. Therefore, specific dimensions can be
determined by those skilled in the art in the light of the
following non-limiting embodiment.
[0020] Further, an embodiment described below is not intended to
limit the invention and is illustrative, and all the features which
are described in the embodiment or the combinations thereof are not
necessarily essential for the invention.
[0021] FIG. 1 shows a shovel according to an embodiment of the
present invention.
[0022] In the shovel, an upper turning body 3 is mounted on an
upper portion of a lower traveling body 1 through a rotation
mechanism 2. The upper turning body 3 is provided with an engine
compartment 3a, a boom 4, an arm 5, a bucket 6, and a cabin 10, and
the like.
[0023] The arm 5 is attached to the tip of the boom 4, and the
bucket 6 is attached to the tip of the arm 5. The boom 4, the arm
5, and the bucket 6 are respectively hydraulically driven by a boom
cylinder 7, an arm cylinder 8, and a bucket cylinder 9.
[0024] In the cabin 10, an operating device 26 (refer to FIG. 2)
which is operated by a driver, and the like are disposed. Further,
in the engine compartment 3a, a power source such as an engine is
mounted.
[0025] In addition, as the shovel according to this embodiment, a
so-called hybrid shovel having a power storage device which stores
electric power which is supplied to a turning drive device is given
as an example. However, the present invention can also be applied
to, for example, an electrically-driven shovel to which charging
power is supplied from an external power supply, and a hydraulic
shovel in which the rotation mechanism 2 is driven by a hydraulic
motor, as long as they are shovels adopting a mechanical brake
(described later).
[0026] FIG. 2 is a block diagram showing the configuration of a
drive system of the shovel. In addition, in FIG. 2, a mechanical
power system is shown by a double line, a high-pressure hydraulic
line is shown by a thick solid line, a pilot line is shown by a
dashed line, and an electric drive and control system is shown by a
thin solid line.
[0027] The drive system of the shovel has an engine 11, a motor
generator 12, a main pump 14, a pilot pump 15, a control valve 17,
the operating device 26, a controller 30, a turning drive device
40, a power storage system, and the like.
[0028] The engine 11 and the motor generator 12 are respectively
connected to two input shafts of a transmission 13. The main pump
14 and the pilot pump 15 are connected to an output shaft of the
transmission 13. Both the main pump 14 and the pilot pump 15 are
hydraulic pumps.
[0029] The control valve 17 is connected to the main pump 14
through a high-pressure hydraulic line 16. Further, the operating
device 26 is connected to the pilot pump 15 through a pilot line
25.
[0030] The control valve 17 performs the control of a hydraulic
system in the hybrid shovel. Accordingly, hydraulic motors 1A and
1B for the lower traveling body, the boom cylinder 7, the arm
cylinder 8, the bucket cylinder 9, and the like are connected to
the control valve 17 through the high-pressure hydraulic lines.
[0031] The motor generator 12 is connected to a power storage
system 120 through an inverter 18. The power storage system 120 has
a capacitor (a power storage device) as an electric condenser.
Further, the power storage system 120 is connected to the turning
drive device 40.
[0032] The turning drive device 40 has an electric motor for
turning 21, a resolver 22, a mechanical brake 23, a turning speed
reducer 24, and the like. The power storage system 120 is connected
to the electric motor for turning 21 through an inverter 20.
Further, an output shaft 21b of the electric motor for turning 21
is connected to the resolver 22 and the turning speed reducer
24.
[0033] The electric motor for turning 21 functions as an electric
motor for turning which drives the upper turning body 3 so as to
turn it. Further, the mechanical brake 23 functions as a brake
device which mechanically applies braking to the upper turning body
3.
[0034] The operating device 26 has a lever 26A, a lever 26B, and a
pedal 26C. The lever 26A, the lever 26B, and the pedal 26C are
respectively connected to the control valve 17 and a pressure
sensor 29 through hydraulic lines 27 and 28. Further, the pressure
sensor 29 is connected to the controller 30 which performs the
drive control of an electric system.
[0035] The controller 30 is a control device as a main control unit
which performs the drive control of the hybrid shovel. The
controller 30 is configured with an arithmetic processing unit
which includes a central processing unit (CPU) and an internal
memory. The controller 30 executes predetermined drive control by
executing a program for drive control stored in the internal memory
by the CPU.
[0036] Specifically, the controller 30 converts a signal which is
supplied from the pressure sensor 29 into a speed command and
performs the drive control of the electric motor for turning 21
based on the signal. At this time, the signal which is supplied
from the pressure sensor 29 is a signal indicating an operation
amount by which a driver operates the operating device 26 in order
to turn the rotation mechanism 2.
[0037] Further, the controller 30 performs the operation control of
the motor generator 12. Here, the operation control of the motor
generator 12 refers to control performing switching between an
electric (assist) operation and a power-generating operation.
[0038] In addition, the controller 30 performs the charge and
discharge control of a capacitor provided in the power storage
system 120. Specifically, the controller 30 performs the switching
control between a step-up operation and a step-down operation of a
step-up/down converter of the power storage system 120 based on a
charge state of the capacitor, an operating state of the motor
generator 12, and an operating state of the electric motor for
turning 21.
[0039] In this embodiment, the operating state of the motor
generator 12 includes two operating states, an electric (assist)
operation state and a power-generating operation state. Further,
the operation state of the electric motor for turning 21 includes
two operating states, a power running operation and a regenerative
operation. In addition, the controller 30 also performs the control
of an amount (a charging current or charging power) which is
charged to the capacitor, as will be described later.
[0040] The shovel having the above-described drive system drives
the electric motor for turning 21 by electric power which is
supplied through the inverter 20, when driving the upper turning
body 3 so as to turn it. The rotary force of the output shaft 21b
of the electric motor for turning 21 is transmitted to an output
shaft 40A of the turning drive device 40 through the turning speed
reducer 24.
[0041] FIG. 3 is a block diagram of the turning drive device 40
which is mounted on the shovel according to an embodiment of the
present invention. The turning drive device 40 has the electric
motor for turning 21, the resolver 22, the mechanical brake 23, the
turning speed reducer 24, the output shaft 40A, and the like.
[0042] The electric motor for turning 21 is an electric motor. The
turning speed reducer 24 is connected to the output shaft side of
the electric motor for turning 21. The turning speed reducer 24 has
a first turning speed reducer 24-1 and a second turning speed
reducer 24-2. Each of the first turning speed reducer 24-1 and the
second turning speed reducer 24-2 is configured with a planetary
gear speed reducer.
[0043] The first turning speed reducer 24-1 of a first stage is
assembled to the electric motor for turning 21. Further, the
mechanical brake 23 is provided at a planetary carrier 46 serving
as an output shaft of the first turning speed reducer 24-1.
Further, the second turning speed reducer 24-2 of a second stage is
assembled to the first turning speed reducer 24-1 with the
mechanical brake 23 interposed therebetween. Then, an output shaft
of the second turning speed reducer 24-2 of the second stage serves
as the output shaft 40A of the turning drive device 40.
[0044] In addition, although not shown in the drawings, the output
shaft 40A of the turning drive device 40 is connected to the
rotation mechanism 2, and the rotation mechanism 2 is driven by the
rotary force of the output shaft 40A.
[0045] Next, a specific configuration of the turning drive device
40 will be described with reference to FIGS. 5 and 6.
[0046] In addition, FIG. 5 is a cross-sectional view of the turning
drive device 40, and FIG. 6 is a cross-sectional view of the
vicinity of the mechanical brake 23 of the turning drive device 40
in an enlarged manner.
[0047] As shown in FIG. 4, the first turning speed reducer 24-1 is
configured with a planetary gear speed reducer having a sun gear
42, a planetary gear 44, the planetary carrier 46, an internal gear
48, and the like. The first turning speed reducer 24-1 is
accommodated in a first gear case 50 and a second gear case 52.
[0048] The sun gear 42 is fixed to the output shaft 21b of the
electric motor for turning 21. In this embodiment, three planetary
gears 44 are engaged with the sun gear 42.
[0049] Each of the planetary gears 44 is rotatably supported on a
pin 44a provided to be erect at the planetary carrier 46. A
flange-shaped portion 44b which prevents the planetary gear 44 from
being separated from the pin 44a is provided at an upper end
portion of the pin 44a. For this reason, the planetary gear 44 is
configured so as not to be separated from the planetary carrier
46.
[0050] Further, each of the planetary gears 44 is engaged with the
internal gear 48 formed in the inner surface of the first gear case
50. The first gear case 50 with the internal gear 48 formed therein
is fixed to an end plate 21a of the electric motor for turning 21.
Accordingly, the internal gear 48 (the first gear case 50) cannot
rotate by itself.
[0051] On the other hand, a lower portion of the planetary carrier
46 serves as the output shaft of the first turning speed reducer
24-1. The planetary carrier 46 serving as the output shaft is
rotatably supported on the second gear case 52 fixed to the first
gear case 50, through a bearing 56.
[0052] The bearing 56 has an inner ring 56a, an outer ring 56b,
balls 56c, and the like (refer to FIG. 6). The inner ring 56a is
disposed integrally with the planetary carrier 46, and the outer
ring 56b is disposed at the second gear case 52. Further, the balls
56c are disposed between the inner ring 56a and the outer ring 56b.
In this way, the planetary carrier 46 can rotate with respect to
the second gear case 52.
[0053] Further, a bearing collar 58 which fixes the bearing 56 to
the planetary carrier 46 is provided at a lower portion of the
bearing 56. In addition, the first turning speed reducer 24-1
having the above-described configuration is lubricated by
lubricating oil LB1.
[0054] In the first turning speed reducer 24-1 having the
configuration as described above, if the output shaft 21b of the
electric motor for turning 21 rotates and thus the sun gear 42
rotates, the planetary gear 44 rotates (rotates on its own axis).
The planetary gear 44 is engaged with the internal gear 48 formed
in the inner surface of the first gear case 50. Accordingly, the
first gear case 50 with the internal gear 48 formed therein tries
to rotate by the rotary force of the planetary gear 44.
[0055] However, the first gear case 50 cannot rotate because it is
fixed to the end plate 21a of the electric motor for turning 21, as
described above. In contrast, the planetary carrier 46 has a
configuration in which it can rotate with respect to the second
gear case 52.
[0056] As a result, the rotary force of the planetary gear 44 acts
as a force to rotate the planetary carrier 46, and thus the
planetary carrier 46 rotates. Due to this, the rotation of the
output shaft 21b of the electric motor for turning 21 is reduced in
speed at the first turning speed reducer 24-1 and is output from
the planetary carrier 46.
[0057] Next, the second turning speed reducer 24-2 will be
described. A sun gear 82 of the second turning speed reducer 24-2
is connected to the planetary carrier 46 serving as the output
shaft of the first turning speed reducer 24-1. The sun gear 82 is
engaged with a plurality of planetary gears 84. In addition, the
planetary gears 84 are engaged with an internal gear 88 formed in
the inner wall of a third gear case 54. Accordingly, the planetary
gear 84 revolves while rotating between the sun gear 82 and the
internal gear 88.
[0058] In this embodiment, the second turning speed reducer 24-2
has three planetary gears 84. Each of the planetary gears 84 is
rotatably supported on a planetary carrier 86 through a pin 84a and
revolves while rotating, thereby rotating the planetary carrier
86.
[0059] Each of the planetary gears 84 is rotatably supported on the
pin 84a provided to be erect at the planetary carrier 86. A
flange-shaped portion 84b which prevents the planetary gear 84 from
being separated from the pin 84a is provided at an upper end
portion of the pin 84a. For this reason, the planetary gear 84 is
configured so as not to be separated from the planetary carrier
86.
[0060] The planetary carrier 86 configures an output shaft of the
second turning speed reducer 24-2. In this embodiment, the second
turning speed reducer 24-2 is a final stage speed reducer.
Accordingly, the planetary carrier 86 serving as the output shaft
of the second turning speed reducer 24-2 serves as the output shaft
40A of the turning speed reducer 24. The second turning speed
reducer 24-2 is lubricated by lubricating oil LB2.
[0061] Due to the above-described configuration, the turning drive
device 40 reduces the rotation speed of the output shaft 21b of the
electric motor for turning 21 and increases the torque of the
output shaft 40A.
[0062] In addition, in this embodiment, the turning speed reducer
24 has been described as being a speed reducer configuration having
a two-stage configuration which is composed of the first turning
speed reducer 24-1 and the second turning speed reducer 24-2.
However, the number of stages of the speed reducers of the turning
speed reducer 24 is not limited thereto and can be appropriately
set based on the output of the electric motor for turning 21,
torque which is required for the rotation mechanism 2, or the
like.
[0063] Next, the mechanical brake 23 will be described.
[0064] The mechanical brake 23 is a displacer brake having a brake
disc 60 and a brake plate 62. The mechanical brake 23 is provided
between the second gear case 52 which is a fixed portion and the
planetary carrier 46 which is an output shaft.
[0065] The brake disc 60 has a disc shape, as shown in FIG. 6, and
an insertion hole 65 into which the planetary carrier 46 is
inserted is formed at the center. Further, spline teeth are formed
in the inner periphery of the insertion hole 65.
[0066] A spline 70 is formed in an outer peripheral portion (a
portion on which the brake disc 60 is mounted) of the planetary
carrier 46. The spline 70 is formed in the outer periphery of the
planetary carrier 46 so as to extend in an up-down direction (a
direction shown by arrows Z1 and Z2 in the drawings).
[0067] In addition, in the following description, the electric
motor for turning 21 side with respect to the planetary carrier 46
is sometimes referred to as an upper side (a side of a direction of
the arrow Z1) and the side opposite to the electric motor for
turning 21 side with respect to the planetary carrier 46 is
sometimes referred to as a lower side (a side of a direction of the
arrow Z2).
[0068] Spline teeth 60a formed in the brake disc 60 are configured
so as to be engaged with the spline 70 formed in the planetary
carrier 46. Accordingly, in a state where the brake disc 60 is
mounted on the planetary carrier 46, a structure in which the brake
disc 60 and the planetary carrier 46 are spline-connected is
made.
[0069] In a state where the brake disc 60 and the planetary carrier
46 are spline-connected in this manner, the brake disc 60 is in a
state of extending toward the outside in a direction of a radius of
rotation from the planetary carrier 46. Further, the brake disc 60
cannot rotate with respect to the planetary carrier 46 but is in a
state of being movable in an axial direction (the direction shown
by the arrows Z1 and Z2 in FIGS. 5 and 6) of the planetary carrier
46.
[0070] The brake plates 62 are disposed on both upper and lower
sides of the brake disc 60. The brake plate 62 has a disc shape
with a hole formed at the center. Further, spline teeth are formed
in the outer periphery of the brake plate 62.
[0071] A spline 72 is formed in an annular inner wall portion (a
portion on which the brake plate 62 is mounted) of the second gear
case 52. The spline 72 is formed in the inner wall of the second
gear case 52 so as to extend in the above-described axial direction
(the direction shown by the arrows Z1 and Z2).
[0072] The spline teeth formed in the brake plate 62 are configured
so as to be engaged with the spline 72 formed in the second gear
case 52. Accordingly, in a state where the brake plate 62 is
mounted on the second gear case 52, a structure in which the brake
plate 62 and the second gear case 52 are spline-connected is
made.
[0073] In a state where the brake plate 62 and the second gear case
52 are spline-connected in this manner, the brake plate 62 is in a
state of extending toward the inside in the direction of a radius
of rotation from the second gear case 52. Further, the brake plate
62 cannot rotate with respect to the second gear case 52 but is in
a state of being movable in the axial direction (the direction
shown by the arrows Z1 and Z2) of the planetary carrier 46.
[0074] Further, a piston 64 is disposed above the upper brake plate
62 in a state of being movable in the axial direction (the
direction shown by the arrows Z1 and Z2) of the planetary carrier
46. The piston 64 is always pressed against the upper brake plate
62 by being pressed by a spring 66.
[0075] As described above, both the brake disc 60 and the brake
plate 62 are movable in the axial direction of the planetary
carrier 46. For this reason, if the brake plate 62 is pressed by
the piston 64, the brake disc 60 is pressed to be sandwiched
between the upper and lower brake plates 62. The brake disc 60 is
pressed to be sandwiched between the brake plates 62, whereby a
brake force to try to prevent the rotation of the brake disc 60 is
generated in the mechanical brake 23.
[0076] As described above, the brake disc 60 has a configuration of
being unable to rotate with respect to the planetary carrier 46.
For this reason, the brake force acting on the brake disc 60
becomes a brake force (a braking force) stopping the rotation of
the planetary carrier 46.
[0077] A hydraulic space 68 to which hydraulic oil can be supplied
is formed between the piston 64 and the second gear case 52.
Further, a brake release port 69 is connected to the hydraulic
space 68. In addition, a seal member 91 such as an O-ring is
disposed between the piston 64 and the second gear case 52 and
performs sealing such that the hydraulic oil in the hydraulic space
68 does not leak.
[0078] The brake release port 69 is connected to the operating
device 26. Then, if oil pressure is supplied from the pilot pump 15
to the hydraulic space 68 through the operating device 26, a
hydraulic line 27a (refer to FIG. 2), and the brake release port
69, the piston 64 is pushed up by the oil pressure. In this way, a
force pressing the brake plate 62 is eliminated, and thus the
mechanical brake 23 enters a state where the brake is released.
[0079] In addition, the mechanical brake 23 having the
above-described configuration is controlled so as to enter a state
where the brake is released at the time of the turning of the upper
turning body 3 and the brake is activated when the upper turning
body 3 has stopped.
[0080] Here, in the turning drive device 40 having the
above-described configuration, attention is paid to the bearing 56
which supports the planetary carrier 46 in the first gear case 50
and the second gear case 52. The planetary carrier 46 is restricted
in position by the bearing 56 and the like, thereby being located
at a predetermined mounting position in the first gear case 50 and
the second gear case 52.
[0081] However, the shovel is used in a harsh environment.
Accordingly, in a case where a great external force is applied to
the upper turning body 3 and each component provided therein at the
time of work, the sun gear 82 configuring the second turning speed
reducer 24-2 is sometimes biased so as to move in a thrust
direction (the direction of the arrow Z1) toward the first turning
speed reducer 24-1 by the external force.
[0082] Since the sun gear 82 is connected to the planetary carrier
46, if the sun gear 82 is biased so as to move in the direction of
the arrow Z1, the planetary carrier 46 is also biased so as to
move, and thus an excessive thrust load is generated in the bearing
56, whereby there is a concern that the bearing 56 may be
damaged.
[0083] In this embodiment, a movement restriction section 130 is
provided, and thus a configuration is made in which even in a case
where the sun gear 82 (the planetary carrier 46) moves, the bearing
56 is protected by the movement restriction section 130.
Hereinafter, the movement restriction section 130 will be
described.
[0084] As shown in an enlarged manner in FIG. 6, the movement
restriction section 130 is fixed to a bottom portion of the first
gear case 50. Further, the movement restriction section 130 is
disposed at a position facing the sun gear 82 provided in the
second turning speed reducer 24-2. The disposition position is also
a boundary position between the first turning speed reducer 24-1
and the second turning speed reducer 24-2.
[0085] The movement restriction section 130 has a thrust plate 132,
a thrust washer 136, a fixing bolt 138, and the like.
[0086] The thrust plate 132 is an annular metal plate in which a
hole into which the output shaft of the planetary carrier 46 is
inserted is formed at the center. The thrust plate 132 has a
predetermined strength capable of restricting the movement of the
sun gear 82 when the sun gear 82 moves, as will be described
later.
[0087] Further, the thrust plate 132 is fixed to a bottom portion
of the second gear case 52 by using a plurality of fixing bolts 138
(in FIG. 6, only one is shown). In the fixing state, the thrust
plate 132 faces the sun gear 82 of the second turning speed reducer
24-2.
[0088] The thrust washer 136 is disposed between the sun gear 82
and the thrust plate 132. The thrust washer 136 receives a force to
the lower side of the sun gear 82, which includes the force of
gravity. Further, the thrust washer 136 performs lubrication
between the sun gear 82 and the thrust plate 132.
[0089] In addition, a bearing member which is disposed between the
sun gear 82 and the thrust plate 132 is not limited to the thrust
washer 136, and it is also possible to use a thrust bearing or the
like.
[0090] Next, an operation of the movement restriction section 130
having the above-described configuration will be described.
[0091] For example, a case where an external force is applied to
the shovel and the sun gear 82 configuring the second turning speed
reducer 24-2 moves toward the first turning speed reducer 24-1 due
to the external force is assumed. That is, a case where the sun
gear 82 moves in the thrust direction (the direction of the arrow
Z1 in the drawings) toward the first turning speed reducer 24-1 is
assumed.
[0092] In this embodiment, the movement restriction section 130 is
disposed at a position facing the sun gear 82. Further, the
movement restriction section 130 is fixed to the second gear case
52. Accordingly, if the sun gear 82 moves in the direction of the
arrow Z1, the sun gear 82 presses the thrust plate 132 through the
thrust washer 136.
[0093] However, the thrust plate 132 is solidly fixed to the second
gear case 52. Further, the strength of the thrust plate 132 is set
to be a strength to withstand a pressing force at which the sun
gear 82 presses the thrust plate 132 due to an external force.
[0094] Therefore, even if the sun gear 82 tries to move, the
movement is restricted by the movement restriction section 130.
Further, the movement of the sun gear 82 is restricted, whereby the
movement of the planetary carrier 46 to which the sun gear 82 is
connected is also restricted. Accordingly, a thrust load in the
thrust direction can be prevented from being generated in the
bearing 56 supporting the planetary carrier 46, and thus damage can
be prevented from occurring in the bearing 56.
[0095] In the embodiment described above, the second turning speed
reducer 24-2 of a lower stage is not constrained with respect to
the respective gear cases 50 and 52 and with respect to the first
turning speed reducer 24-1 of an upper stage. In the second turning
speed reducer 24-2 of the lower stage, in terms of the
configuration thereof, there is a possibility that due to an
external force or the like, the sun gear 82 may move up and down
alone or the second turning speed reducer 24-2 (the sun gear 82,
the planetary gear 84, the planetary carrier 86, and the internal
gear 88) may move up and down as a whole.
[0096] However, in this embodiment, as described above, the
movement can be received by the movement restriction section 130,
and therefore, the occurrence of damage to the bearing 56 due to
contact can be prevented. In particular, in a case where the
turning speed reducer 24 has a two-stage configuration and a lower
stage is a configuration such as the second turning speed reducer
24-2, the present invention is particularly effective.
[0097] A preferred embodiment of the present invention has been
described above in detail. However, the present invention is not
limited to the specific embodiment described above, and various
modification and changes can be made within the scope of the
concept of the present invention stated in the appended claims.
[0098] For example, in the embodiment described above, the movement
restriction section 130 is configured by fixing the thrust plate
132 to the first gear case 50 by the fixing bolt 138. However, it
is also possible to form a movement restriction section integrally
with the first gear case 50.
[0099] It should be understood that the invention is not limited to
the above-described embodiment, and may be modified into various
forms on the basis of the spirit of the invention. Additionally,
the modifications are included in the scope of the invention.
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